flyrotary@lancaironline.net Mailing List Archive

Message

Bob,

Mine engine didn't backfire or anything. I just noticed a surge. It happened a couple of times at the beginning of the takeoff roll, but the last time was during the take off climb, and it did it three times. The engine would rev, just like pushing in on a clutch, and then would grab again after about 1 second. Tracy said that the gear was re-welding itself to the shaft, from the heat during the slipping.

Steve Brooks

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Rogers, Bob J.
Sent: Tuesday, January 10, 2006 11:29 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] RD-1B Service alert

I am wondering how much stronger the drilling and pinning is than the welding of the input shaft. Are there any disadvantages or drawbacks to drilling and pinning (other than the effort involved in making the modification)? As I understand it, Dave Leonard’s engine was backfiring when the shaft broke (I do not know about Steve Brook’s incident). Absent some abnormal torque pulses, such as backfiring, can we still expect that a 13B Turbo engine will break a welded shaft? If drilling and pinning is the superior method, why wasn’t that method used to begin with?

Bob Rogers

(agonizing over having to remove my RD-1B Redrive - again)

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Tracy Crook
Sent: Saturday, January 07, 2006 10:52 AM
To: Rotary motors in aircraft
Subject: RD-1B Service alert

Service Alert on B drives

I will publish a service alert later today on the website (www.rotaryaviation.com) on B drives used on turbo charged 13Bs and 20B engines.

Decided to do this after reviewing Steve Brooks input shaft problem. His input shaft was previously used for well over 100 hours on Ed Anderson's drive (fairly early drive) with no problems. It used the welded style sun gear attachment to the input shaft. Steve's turbo engine apparently had enough torque to break the weld in the same way that Dave Leonard's (another turbo) did.

Shortly before starting C drive production (4-23-03) we changed over to a drilled and pinned input shaft. This service alert requests (strongly) that any B drive used on a turbo charged 13B or 20B engine delivered before this date be inspected for presence of a pinned input shaft. If the sun gear is welded instead of pinned, the input shaft should be returned to RWS to have it drilled and pinned prior to any flight. This service will be performed for only the cost of materials and shipping. No problems have been encountered on RD-1, RD-1A or RD-1B drives used on normally aspirated engines but if you wish, this update can be done for a nominal service charge ( parts & shipping + shop time TBD).

[snip]

Tracy